This application claims the priority benefit of Taiwan application serial no. 92106255, filed Mar. 21, 2003.
1. Field of the Invention
The present invention relates in general to semiconductor circuit components and a method of fabrication. In particular, the present invention relates to the fabrication of metal bonding for device dice of semiconductor circuit components utilizing prescribed feeds of metal balls.
2. Technical Background
Core circuit devices of semiconductor circuit components, either integrated or discrete, are fabricated on silicon wafers in batches of multiple dice. After the wafer fabrication stage, each circuit component die needs to be secured to and hermetically sealed in an enclosure, frequently plastic or ceramic, and becomes a useful circuit component for assembly onto the printed circuit board of an electronic equipment. An important step in this packaging process is bonding, the electrical connection of contact pads on the component die to their corresponding pins of the package.
Various types of electrical connection are used for different circuit components. For example, joining is a scheme connecting the die circuitry to the package relying on pure mechanically pressed contact. Joining is found primarily in discrete circuit components such as diodes that mechanically press the electrical contact of a circuit die onto its corresponding package lead. Joining is susceptible to fluctuations of environmental factors and is generally unreliable.
Another method of electrical connection between circuit dice and their package pins or leads popularly used in integrated circuits and some discrete components involves the bonding of both the device die and the die contact pads. The device die is fixedly secured to a substrate in the die-bonding process, while wire-bonding connects a length of wire of selected metal or alloy between the contact pads on the circuit die and their corresponding pins of the package. In the case of ICs, this wire-bonding facilitates the wired connection between contact pads distributed around the periphery of the IC die and their corresponding connection points on the lead-frame of the chip carrier (package). Although straightforward, however, die- and wire-bonding is relatively tedious, time-consuming and costly as mechanical maneuvering is necessary for each bonding.
Note that bonding provided by hardened metal grain-containing bonding pastes can not be considered metal bond. The resin-based material embedding the metal grains is susceptible to changes in environmental factors, temperature and humidity in particular. More, these conventional methods, die-/wire-bonding and similar inclusive, are not suitable for large-power applications such as power diodes.
Some prior-art components, power transistor and diodes in particular, require the stability and strong bond provided by metal bonding due to thermal stresses arising from their operation. However, conventional metal bonding has been relying on rare and expensive metals such as rhodium, molybdenum and platinum so that manufacturing costs are high.
It is therefore an object of the present invention to provide a method of fabricating metal bonding for semiconductor circuit components between die electrical contacts and package electrical leads that is reliable within the temperature ranges during both fabrication and operation of circuit components.
It is another object of the present invention to provide a method of fabricating reliable metal bonding for semiconductor circuit components at low costs.
In order to achieve the above and other objects, the present invention provides a method for the fabrication of metal bonding for a semiconductor circuit component employing prescribed feed of metal ball. The metal bonding fabrication method comprises the steps of, first, placing a metal ball at the metallization site on the surface of the circuit die of the component; then, melting the metal ball on the site; and subsequently solidifying the molten metal and forming a metal bump at the sit